Lighting device with variable color rendering

ABSTRACT

The present disclosure relates to an LED-based lighting component that can control the color rendering capability of its generated light based on the presence or characteristics of ambient light. In one embodiment, the lighting component may employ at least two different types of LEDs to generate light. Control circuitry of the lighting component is able to monitor ambient light and drive the LEDs based on an ambient light characteristic that is indicative of the CRI of the ambient light. If the ambient light characteristic is indicative of the ambient light having a lower CRI, the control system will drive the LEDs to emit light with a defined CRI. If the ambient light characteristic is indicative of the ambient light having a higher CRI, the control system will drive the LEDs to emit light with a reduced CRI, which is lower than the defined CRI.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.13/561,388 filed on Jul. 30, 2012 and subsequently issuing as U.S. Pat.No. 9,066,405 on Jun. 23, 2015, wherein the foregoing patent applicationand patent are hereby incorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to a high quality solid-state lightingdevice that can control the color rendering capability of its emittedlight based on ambient light.

BACKGROUND

The color quality of a light source relates to the ability of the lightsource to faithfully reproduce the colors of objects illuminated by thelight source, in comparison with natural light. As expected, the colorquality of the light source is an important characteristic of the lightsource in general, and to consumers in particular. Most consumers wantan object that appears red in natural light to appear the same color ofred when illuminated by the light source. For example, a light sourcewith poor color quality may cause the red object to appear anywhere fromorange to brown when illuminated.

The Color Rendering Index (CRI) is a measure of the relative colorquality of a light source with respect to natural light. The CRI is theonly internationally accepted standard for measuring color quality andis defined by the International Commission on Illumination (CIE orCommission internationale de l'éclairage). At a high level, the CRI fora light source is calculated by initially measuring the color appearanceof 14 reflective samples of different defined hues under both areference source and the light source being measured. The measured colorappearances are then modified for chromatic adaptation with a Von Kirescorrection. After modification, the difference in the color appearancefor each reflective sample i is referred to as the color appearancedifference, ΔE_(i).

Based on the corresponding color appearance difference, ΔE_(i), aspecial CRI, R_(i), is calculated for each reflective sample using theformula: R_(i)=100-4.6ΔE_(i). To calculate the general CRI, R_(a), forthe light source, an average of the special CRI, R_(i), for only thefirst eight of the reflective samples is calculated, wherein:

$R_{a} = {\frac{1}{8}{\sum\limits_{i = 1}^{8}R_{i}}}$A perfect CRI of 100 indicates that there are essentially no colordifferences for any of the eight reflective samples that are used tocalculate the general CRI R_(a).

For reference, natural sunlight has a high CRI R_(a) of approximately100, and incandescent light has a CRI R_(a) of 95 or greater. Florescentlighting is less accurate and generally has a CRI R_(a) of 70-80, whichis on the lower end of what is acceptable for residential and indoorcommercial lighting applications. Street lamps that use mercury vapor orsodium lamps often have a relatively poor CRI R_(a) of around 40 orlower.

The CRI of a light source only considers color rendering, as the nameimplies, and ignores many other attributes that impact overall colorquality, such as chromatic discrimination and common observerpreferences. Even as a measure of color rendering, CRI is calculatedusing only eight of the 14 reflective samples, as noted above. Theseeight reflective samples are all of low to medium chromatic saturationand do not span the range of normal visible colors. Thus, the CRIcalculations do not take into consideration the ability of the lightsource to properly render highly saturated colors. As a result, lightsources that render colors of low saturation well, but perform poorlywith highly saturated colors can achieve relatively high CRIs, whilelight sources that afford high chromatic discrimination are pleasing tothe common observer, and perform relatively well for colors at allsaturation levels may have a relatively low CRI.

The use of the CRI as a reliable color quality metric for solid-statelighting sources, such as those employing light emitting diodes (LEDs),is particularly problematic given the inherently peaked light spectrumof LEDs. Depending on how the spectrum of a given LED light sourcealigns with the reflective samples used to calculate the CRI, theresulting CRI may not be a fair representation of the perceived colorquality of the LED light source in comparison with other LED lightsources with different light spectra as well as with other traditionallight sources. For example, a well-designed LED lighting source with alower CRI R_(a) of 80 may be perceived as having a much more accurateand pleasing color rendering than a florescent lighting source with sameCRI R_(a) of 80. Similarly, a first LED lighting source that isengineered to achieve a higher CRI R_(a) of 90 may not be perceived asbeing able to render colors as well as a second LED lighting source witha lower CRI R_(a).

Given the limitations of the CRI as a measure of color quality forsolid-state lighting devices, a new color quality metric, which isreferred to as the Color Quality Scale (CQS), has been developed by theNational Institute of Standards and Technology (NIST). Instead of usingonly eight low-chroma samples that do not span the full range of hues,the CQS takes in to consideration 15 Munsell samples that have muchhigher chroma and are spaced evenly along the entire hue circle. CQSalso takes in to consideration various other characteristics that havebeen determined to impact an observer's perception of color quality. TheCQS has a range of 0-100, with 100 being a perfect score. The details ofhow CQS is measured as of the date of filing is provided in Appendix A,an article entitled “Color Rendering of Light Sources,” from theNational Institute of Standards and Technology web site(http://physics.nist.gov/Divisions/Div844/facilities/vision/color.html),accessed on Mar. 11, 2009 and incorporated herein by reference in itsentirety.

Accordingly, CRI and CQI provide exemplary, but non-limiting, colorrendering metrics upon which the color rendering of alight source arejudged.

SUMMARY

The present disclosure relates to an LED-based lighting component thatcan control the color rendering capability of its generated light basedon the presence or characteristics of ambient light. In one embodiment,the lighting component may employ at least two different types of LEDsto generate light. Control circuitry of the lighting component is ableto monitor ambient light and drive the LEDs based on an ambient lightcharacteristic that is indicative of the CRI of the ambient light. Ifthe ambient light characteristic is indicative of the ambient lighthaving a lower CRI, the control system will drive the LEDs to emit lightwith a defined CRI. If the ambient light characteristic is indicative ofthe ambient light having a higher CRI, the control system will drive theLEDs to emit light with a reduced CRI, which is lower than the definedCRI.

For instance, when there is no ambient light or ambient light having alower CRI, the lighting component may operate normally and emit lighthaving the defined CRI. In the presence of significant ambient lightfrom sunlight, which naturally has a high CRI, or other source that iscapable of providing ambient light with a relatively high CRI, thelighting component may adjust how the LEDs are driven to emit light at alower CRI. The reduction in CRI of the emitted light may correspond toan increase in overall system efficiency, efficacy of the emitted light,a reduction in power consumption, or the like while maintainingperceived brightness.

In a first embodiment, a lighting component is provided with a pluralityof LEDs and control circuitry for driving the plurality of LEDs. Thecontrol circuitry is adapted to monitor an ambient light characteristicof ambient light through an ambient light sensor, a separate LED, or oneof the plurality of LEDs. In response to the monitored ambient lightcharacteristic, the control circuitry may either: drive the LEDs toprovide light having a reduced color rendering metric, if the ambientlight characteristic is indicative of the ambient light having a highercolor rendering metric, or drive the LEDs to provide light having anormal color rendering metric, if the ambient light characteristic isindicative of the ambient light having a lower coloring renderingmetric. In this embodiment, the reduced color rendering metric is lowerthan the normal color rendering metric.

The plurality of LEDs may have at least one LED of a first type and atleast one LED of a second type, wherein the control circuitry is adaptedto drive the at least one LED of the first type with less current whenproviding the light with the reduced color rendering metric than whenproviding the light with the normal color rendering metric.

In certain configurations, the LED of the first type is less efficientthan the LED of the second type and may provide light with the ambientlighting characteristic more effectively than the LED of the secondtype. The LED of the first type may be less efficient than the LED ofthe second type, and may provide light with the ambient lightingcharacteristic more effectively than the LED of the second type.

As an example, the LED of the first type may generate a predominantlyreddish light and the LED of the second type may generate predominantlyeither a greenish or yellowish light such that the reddish light fromthe at least one LED of the first type and the greenish or yellowishlight from the at least one LED of the second type mix to provide whitelight. As such, the ambient light characteristic of the ambient lightthat is being monitored may correspond to an amount of reddish light inthe ambient light. In more general terms, the LED of the first typegenerates predominantly a first color of light and the LED of the secondtype generates predominantly a second color of light that is differentfrom the first color of light. The first color of light from the LED ofthe first type and the second color of light from the LED of the secondtype mix to provide white light.

In another example, the LED of the first type generates predominantly awhite light at a lower efficiency, and the LED of the second typegenerates white light at a higher efficiency. As such, the white lightfrom the LED of the first type and the white light from the LED of thesecond type mix to provide white light at a desired color temperature.

The color rendering metric in select embodiments corresponds to CRI orCQI. Further, the ambient light sensor may take on differentconfigurations. In a first configuration, the ambient light sensor isseparate from the main LEDs and is associated with the control circuitryto facilitate monitoring of the ambient light characteristic. Theambient light sensor may be a specially configured light sensor oranother LED that is configured to generate a current indicative of theambient light characteristic in response to being exposed to the ambientlight. If the plurality of LEDs are driven with pulses of current, theambient light characteristic may be monitored between any two pulses ofcurrent. Alternatively, one or more of the main LEDs may be used by thecontrol circuitry to monitor the ambient light characteristic. Again, ifthe LEDs are driven with pulses of current, the ambient lightcharacteristic may be monitored between any two pulses of current.

In select embodiments, the light having the normal color renderingmetric that is provided during normal operation and the light having thereduced color rendering metric during reduced color rendering mode havesubstantially the same intensity. The lighting component may consumeless power when providing the light having the reduced color renderingmetric than when providing the light having the normal color renderingmetric. The lighting component may also be more efficient when providingthe light having the reduced color rendering metric than when providingthe light having the normal color rendering metric.

In another embodiment, the control circuitry is configured to initiallydrive the LEDs to provide light having a normal color rendering metricand then begin monitoring the ambient light characteristic of theambient light. When the ambient light characteristic of the ambientlight reaches a defined threshold, the control circuitry will drive theLEDs to provide light having the reduced color rendering metric.

Those skilled in the art will appreciate the scope of the disclosure andrealize additional aspects thereof after reading the following detaileddescription in association with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thisspecification illustrate several aspects of the disclosure, and togetherwith the description serve to explain the principles of the disclosure.

FIG. 1 is an isometric view of the front of an exemplary lightingfixture in which a lighting device according to one embodiment of thedisclosure may be implemented.

FIG. 2 is an isometric view of the back of the lighting fixture of FIG.1.

FIG. 3 is an exploded isometric view of the lighting fixture of FIG. 1.

FIG. 4 is an isometric view of the front of the lighting fixture of FIG.1 without the lens, diffuser, and reflector.

FIG. 5 is an isometric view of the front of the lighting fixture of FIG.1 without the lens and diffuser.

FIG. 6 is a cross sectional view of the lighting fixture of FIG. 5.

FIG. 7 is a cross-sectional view of a first type of LED architecture.

FIG. 8 is a cross-sectional view of a second type of LED architecture.

FIG. 9A is a schematic of exemplary control module electronics accordingto a first embodiment of the disclosure.

FIG. 9B is a schematic of exemplary control module electronics accordingto a second embodiment of the disclosure.

FIG. 9C is a schematic of exemplary control module electronics accordingto a third embodiment of the disclosure.

FIG. 9D is a schematic of exemplary control module electronics accordingto a fourth embodiment of the disclosure.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the disclosure andillustrate the best mode of practicing the disclosure. Upon reading thefollowing description in light of the accompanying drawings, thoseskilled in the art will understand the concepts of the disclosure andwill recognize applications of these concepts not particularly addressedherein. It should be understood that these concepts and applicationsfall within the scope of the disclosure.

It will be understood that relative terms such as “front,” “forward,”“rear,” “below,” “above,” “upper,” “lower,” “horizontal,” or “vertical”may be used herein to describe a relationship of one element, layer orregion to another element, layer or region as illustrated in thefigures. It will be understood that these terms are intended toencompass different orientations of the device in addition to theorientation depicted in the figures.

The present disclosure relates to a solid-state lighting device thatemploys at least two different types of LEDs to generate light. Controlcircuitry of the lighting device is able to monitor ambient light anddrive the LEDs based on an ambient light characteristic that isindicative of the color rendering metric of the ambient light. Exemplarycolor rendering metrics are CRI and CQI. If the ambient lightcharacteristic is indicative of the ambient light having a lower colorrendering metric, the control system will drive the LEDs to emit lightwith a defined color rendering metric. If the ambient lightcharacteristic is indicative of the ambient light having a higher colorrendering metric, the control system will drive the LEDs to emit lightwith a reduced color rendering metric, which is lower than the definedcolor rendering metric.

For context and ease of understanding, the following description firstdescribes an exemplary solid-state lighting fixture prior to describinghow the solid-state lighting fixture may be configured to function assummarized above. With reference to FIGS. 1 and 2, a unique lightingfixture 10 is illustrated according to one embodiment of the presentdisclosure. While this particular lighting fixture 10 is used forreference, those skilled in the art will recognize that virtually anytype of solid-state lighting fixture may benefit from the subjectdisclosure.

As shown, the lighting fixture 10 includes a control module 12, amounting structure 14, and a lens 16. The illustrated mounting structure14 is cup-shaped and is capable of acting as a heat spreading device;however, different fixtures may include different mounting structures 14that may or may not act as heat spreading devices. A light source (notshown), which will be described in detail further below, is mountedinside the mounting structure 14 and oriented such that light is emittedfrom the mounting structure through the lens 16. The electronics (notshown) that are required to power and drive the light source areprovided, at least in part, by the control module 12. While the lightingfixture 10 is envisioned to be used predominantly in 4, 5, and 6 inchrecessed lighting applications for industrial, commercial, andresidential applications, those skilled in the art will recognize thatthe concepts disclosed herein are applicable to virtually any sizelighting device and any type of lighting application.

The lens 16 may include one or more lenses that are made of clear ortransparent materials, such as polycarbonate (PC), acrylic (PMMA),glass, or any other suitable material. As discussed further below, thelens 16 may be associated with a diffuser for diffusing the lightemanating from the light source and exiting the mounting structure 14via the lens 16. Further, the lens 16 may also be configured to shape ordirect the light exiting the mounting structure 14 via the lens 16 in adesired manner.

The control module 12 and the mounting structure 14 may be integratedand provided by a single structure. Alternatively, the control module 12and the mounting structure 14 may be modular wherein different sizes,shapes, and types of control modules 12 may be attached, or otherwiseconnected, to the mounting structure 14 and used to drive the lightsource provided therein.

In the illustrated embodiment, the mounting structure 14 is cup-shapedand includes a sidewall 18 that extends between a bottom panel 20 at therear of the mounting structure 14, and a rim, which may be provided byan annular flange 22 at the front of the mounting structure 14. One ormore elongated slots 24 may be formed in the outside surface of thesidewall 18. There are two elongated slots 24, which extend parallel toa central axis of the lighting fixture 10 from the rear surface of thebottom panel 20 toward, but not completely to, the annular flange 22.The elongated slots 24 may be used for a variety of purposes, such asproviding a channel for a grounding wire that is connected to themounting structure 14 inside the elongated slot 24, connectingadditional elements to the lighting fixture 10, or as described furtherbelow, securely attaching the lens 16 to the mounting structure 14.

The annular flange 22 may include one or more mounting recesses 26 inwhich mounting holes are provided. The mounting holes may be used formounting the lighting fixture 10 to a mounting structure or for mountingaccessories to the lighting fixture 10. The mounting recesses 26 providefor counter-sinking the heads of bolts, screws, or other attachmentmeans below or into the front surface of the annular flange 22.

With reference to FIG. 3, an exploded view of the lighting fixture 10 ofFIGS. 1 and 2 is provided. As illustrated, the control module 12includes control module electronics 28, which are enclosed by a controlmodule housing 30 and a control module cover 32. The control modulehousing 30 is cup-shaped and sized sufficiently to receive the controlmodule electronics 28. The control module cover 32 provides a cover thatextends substantially over the opening of the control module housing 30.Once the control module cover 32 is in place, the control moduleelectronics 28 are contained within the control module housing 30 andthe control module cover 32. The control module 12 is, in theillustrated embodiment, mounted to the rear surface of the bottom panel20 of the mounting structure 14.

The control module electronics 28 may be used to provide all or aportion of power and control signals necessary to power and control thelight source 34, which may be mounted on the front surface of the bottompanel 20 of the mounting structure 14 as shown, or in an apertureprovided in the bottom panel 20 (not shown). Aligned holes or openingsin the bottom panel 20 of the mounting structure 14 and the controlmodule cover 32 are provided to facilitate an electrical connectionbetween the control module electronics 28 and the light source 34. In analternative embodiment (not shown), the control module 12 may provide athreaded base that is configured to screw into a conventional lightsocket wherein the lighting fixture resembles or is at least acompatible replacement for a conventional light bulb. Power to thelighting fixture 10 would be provided via this base.

In the illustrated embodiment, the light source 34 is solid state andemploys light emitting diodes (LEDs) and associated electronics, whichare mounted to a printed circuit board (PCB) to generate light at adesired color, intensity and color temperature. The LEDs are mounted onthe front side of the PCB while the rear side of the PCB is mounted tothe front surface of the bottom panel 20 of the mounting structure 14directly or via a thermally conductive pad (not shown). In thisembodiment, the thermally conductive pad has a low thermal resistivity,and therefore, efficiently transfers heat that is generated by the lightsource 34 to the bottom panel 20 of the mounting structure 14.

While various mounting mechanisms are available, the illustratedembodiment employs four bolts 44 to attach the PCB of the light source34 to the front surface of the bottom panel 20 of the mounting structure14. The bolts 44 screw into threaded holes provided in the front surfaceof the bottom panel 20 of the mounting structure 14. Three bolts 46 areused to attach the mounting structure 14 to the control module 12. Inthis particular configuration, the bolts 46 extend through correspondingholes provided in the mounting structure 14 and the control module cover32 and screw into threaded apertures (not shown) provided just insidethe rim of the control module housing 30. As such, the bolts 46effectively sandwich the control module cover 32 between the mountingstructure 14 and the control module housing 30.

A reflector cone 36 resides within the interior chamber provided by themounting structure 14. In the illustrated embodiment, the reflector cone36 has a conical wall that extends between a larger front opening and asmaller rear opening. The larger front opening resides at andsubstantially corresponds to the dimensions of front opening in themounting structure 14 that corresponds to the front of the interiorchamber provided by the mounting structure 14. The smaller rear openingof the reflector cone 36 resides about and substantially corresponds tothe size of the LED or array of LEDs provided by the light source 34.The front surface of the reflector cone 36 is generally, but notnecessarily, highly reflective in an effort to increase the overallefficiency and optical performance of the lighting fixture 10. Incertain embodiments, the reflector cone 36 is formed from metal, paper,a polymer, or a combination thereof. In essence, the reflector cone 36provides a mixing chamber for light emitted from the light source 34 andmay be used to help direct or control how the light exits the mixingchamber through the lens 16.

When assembled, the lens 16 is mounted on or over the annular flange 22and may be used to hold the reflector cone 36 in place within theinterior chamber of the mounting structure 14 as well as hold additionallenses and one or more planar diffusers 38 in place. In the illustratedembodiment, the lens 16 and the diffuser 38 generally correspond inshape and size to the front opening of the mounting structure 14 and aremounted such that the front surface of the lens 16 is substantiallyflush with the front surface of the annular flange 22. As shown in FIGS.4 and 5, a recess 48 is provided on the interior surface of the sidewall18 and substantially around the opening of the mounting structure 14.The recess 48 provides a ledge on which the diffuser 38 and the lens 16rest inside the mounting structure 14. The recess 48 may be sufficientlydeep such that the front surface of the lens 16 is flush with the frontsurface of the annular flange 22.

Returning to FIG. 3, the lens 16 may include tabs 40, which extendrearward from the outer periphery of the lens 16. The tabs 40 may slideinto corresponding channels on the interior surface of the sidewall 18(see FIG. 4). The channels are aligned with corresponding elongatedslots 24 on the exterior of the sidewall 18. The tabs 40 have threadedholes that align with holes provided in the grooves and elongated slots24. When the lens 16 resides in the recess 48 at the front opening ofthe mounting structure 14, the holes in the tabs 40 will align with theholes in the elongated slots 24. Bolts 42 may be inserted through theholes in the elongated slots and screwed into the holes provided in thetabs 40 to affix the lens 16 to the mounting structure 14. When the lens16 is secured, the diffuser 38 is sandwiched between the lens and therecess 48, and the reflector cone 36 is contained between the diffuser38 and the light source 34. Alternatively, a retention ring (not shown)may attach to the flange 22 of the mounting structure 14 and operate tohold the lens 16 and diffuser 38 in place.

The degree and type of diffusion provided by the diffuser 38 may varyfrom one embodiment to another. Further, color, translucency, oropaqueness of the diffuser 38 may vary from one embodiment to another.Separate diffusers 38, such as that illustrated in FIG. 3, are typicallyformed from a thermoplastic, glass, or ceramic, but other materials areviable and will be appreciated by those skilled in the art. Similarly,the lens 16 is planar and generally corresponds to the shape and size ofthe diffuser 38 as well as the front opening of the mounting structure14. As with the diffuser 38, the material, color, translucency, oropaqueness of the lens 16 may vary from one embodiment to another.Further, both the diffuser 38 and the lens 16 may be formed from one ormore materials or one or more layers of the same or different materials.While only one diffuser 38 and one lens 16 are depicted, the lightingfixture 10 may have multiple diffusers 38 or lenses 16.

For LED-based applications, the light source 34 provides an array ofLEDs 50, as illustrated in FIG. 4. FIG. 4 illustrates a front isometricview of the lighting fixture 10, with the lens 16, diffuser 38, andreflector cone 36 removed, such that the light source 34 and the arrayof LEDs 50 are clearly visible within the mounting structure 14. FIG. 5illustrates a front isometric view of the lighting fixture 10 with thelens 16 and diffuser 38 removed and the reflector cone 36 in place, suchthe array of LEDs 50 of the light source 34 are aligned with the rearopening of the reflector cone 36. As noted above, the volume inside thereflector cone 36 and bounded by the rear opening of the reflector cone36 and the lens 16 or diffuser 38 provides a mixing chamber.

Light emitted from the array of LEDs 50 is mixed inside the mixingchamber formed by the reflector cone 36 (not shown) and directed outthrough the lens 16 in a forward direction to form a light beam. Thearray of LEDs 50 of the light source 34 may include LEDs 50 that emitdifferent colors of light. For example, the array of LEDs 50 may includeboth red LEDs that emit reddish light and blue-shifted yellow (BSY) LEDsthat emit bluish-yellow light or blue-shifted green (BSG) LEDs that emitbluish-green light, wherein the reddish and bluish-yellow orbluish-green light is mixed to form “white” light at a desired colortemperature. In certain embodiments, the array of LEDs may include alarge number of red LEDs and BSY or BSG LEDs in various ratios. Forexample, five or six BSY or BSG LEDs may surround each red LED, and thetotal number of LEDs may be 25, 50, 100, or more depending on theapplication. FIGS. 4, 5, and 6 only show 9 LEDs in the array of LEDs forclarity. While red and either BSY or BSG LEDs are provided as anexample, various combinations of LEDs may be used. For example, amixture of red, green, and blue LEDs may be used. Further, the mixturemay include different types of LEDs for any given color. For example,the mixture could include different types of blue LEDs and green LEDswith a single type of red LED.

For a uniformly colored beam, relatively thorough mixing of the lightemitted from the array of LEDs 50 is desired. Both the reflector cone 36and the diffusion provided by the diffuser 38 play significant roles inmixing the light emanated from the array of LEDs 50 of the light source34. In particular, certain light rays, which are referred to asnon-reflected light rays, emanate from the array of LEDs 50 and exit themixing chamber through the diffuser 38 and lens 16 without beingreflected off of the interior surface of the reflector cone 36. Otherlight rays, which are referred to as reflected light rays, emanate fromthe array of LEDs 50 of the light source 34 and are reflected off of thefront surface of the reflector cone 36 one or more times before exitingthe mixing chamber through the diffuser 38 and lens 16. With thesereflections, the reflected light rays are effectively mixed with eachother and at least some of the non-reflected light rays within themixing chamber before exiting the mixing chamber through the diffuser 38and the lens 16.

As noted above, the diffuser 38 functions to diffuse, and as result mix,the non-reflected and reflected light rays as they exit the mixingchamber, wherein the mixing chamber and the diffuser 38 provide thedesired mixing of the light emanated from the array of LEDs 50 of thelight source 34 to provide a light beam of a consistent color. Inaddition to mixing light rays, the lens 16 and diffuser 38 may bedesigned and the reflector cone 36 shaped in a manner to control therelative concentration and shape of the resulting light beam that isprojected from the lighting fixture 10. For example, a first lightingfixture 10 may be designed to provide a concentrated beam for aspotlight, wherein another may be designed to provide a widely dispersedbeam for a floodlight. From an aesthetics perspective, the diffusionprovided by the diffuser 38 also prevents the emitted light from lookingpixelated and obstructs the ability for a user to see the individualLEDs of the array of LEDs 50.

As provided in the above embodiment, the more traditional approach todiffusion is to provide a diffuser 38 that is separate from the lens 16.As such, the lens 16 is effectively transparent and does not add anyintentional diffusion. The intentional diffusion is provided by thediffuser 38. In most instances, the diffuser 38 and lens 16 arepositioned next to one another as shown in FIG. 6. However, in otherembodiments, the diffusion may be integrated into the lens 16 itself.

A traditional package for an LED 52 of the array of LEDs 50 isillustrated in FIG. 7. A single LED chip 54 is mounted on a reflectivecup 56 using solder or a conductive epoxy, such that ohmic contacts forthe cathode (or anode) of the LED chip 54 are electrically coupled tothe bottom of the reflective cup 56. The reflective cup 56 is eithercoupled to or integrally formed with a first lead 58 of the LED 52. Oneor more bond wires 60 connect ohmic contacts for the anode (or cathode)of the LED chip 54 to a second lead 62.

The reflective cup 56 may be filled with an encapsulant material 64 thatencapsulates the LED chip 54. The encapsulant material 64 may be clearor may contain a wavelength conversion material, such as a phosphor,which is described in greater detail below. The entire assembly isencapsulated in a clear protective resin 66, which may be molded in theshape of a lens to control the light emitted from the LED chip 54.

An alternative package for an LED 52 is illustrated in FIG. 8 whereinthe LED chip 54 is mounted on a substrate 67. In particular, the ohmiccontacts for the anode (or cathode) of the LED chip 54 are directlymounted to first contact pads 68 on the surface of the substrate 67. Theohmic contacts for the cathode (or anode) of the LED chip 54 areconnected to second contact pads 70, which are also on the surface ofthe substrate 67, using bond wires 72. The LED chip 54 resides in acavity of a reflector structure 74, which is formed from a reflectivematerial and functions to reflect light emitted from the LED chip 54through the opening formed by the reflector structure 74. The cavityformed by the reflector structure 74 may be filled with an encapsulantmaterial 64 that encapsulates the LED chip 54. The encapsulant material64 may be clear or may contain a wavelength conversion material, such asa phosphor.

In either of the embodiments of FIGS. 7 and 8, if the encapsulantmaterial 64 is clear, the light emitted by the LED chip 54 passesthrough the encapsulant material 64 and the protective resin 66 withoutany substantial shift in color. As such, the light emitted from the LEDchip 54 is effectively the light emitted from the LED 52. If theencapsulant material 64 contains a wavelength conversion material,substantially all or a portion of the light emitted by the LED chip 54in a first wavelength range may be absorbed by the wavelength conversionmaterial, which will responsively emit light in a second wavelengthrange. The concentration and type of wavelength conversion material willdictate how much of the light emitted by the LED chip 54 is absorbed bythe wavelength conversion material as well as the extent of thewavelength conversion. In embodiments where some of the light emitted bythe LED chip 54 passes through the wavelength conversion materialwithout being absorbed, the light passing through the wavelengthconversion material will mix with the light emitted by the wavelengthconversion material. Thus, when a wavelength conversion material isused, the light emitted from the LED 52 is shifted in color from theactual light emitted from the LED chip 54.

As noted above, the array of LEDs 50 may include a group of BSY or BSGLEDs 52 as well as a group of red LEDs 52. BSY LEDs 52 include an LEDchip 54 that emits bluish light, and the wavelength conversion materialis a yellow phosphor that absorbs the blue light and emits yellowishlight. Even if some of the bluish light passes through the phosphor, theresultant mix of light emitted from the overall BSY LED 52 is yellowishlight. The yellowish light emitted from a BSY LED 52 has a color pointthat falls above the Black Body Locus (BBL) on the 1931 CIE chromaticitydiagram wherein the BBL corresponds to the various color temperatures ofwhite light.

Similarly, BSG LEDs 52 include an LED chip 54 that emits bluish light;however, the wavelength conversion material is a greenish phosphor thatabsorbs the blue light and emits greenish light. Even if some of thebluish light passes through the phosphor, the resultant mix of lightemitted from the overall BSG LED 52 is greenish light. The greenishlight emitted from a BSG LED 52 has a color point that falls above theBBL on the 1931 CIE chromaticity diagram wherein the BBL corresponds tothe various color temperatures of white light.

The red LEDs 52 generally emit reddish light at a color point on theopposite side of the BBL as the yellowish or greenish light of the BSYor BSG LEDs 52. As such, the reddish light from the red LEDs 52 mixeswith the yellowish or greenish light emitted from the BSY or BSG LEDs 52to generate white light that has a desired color temperature and fallswithin a desired proximity of the BBL. In effect, the reddish light fromthe red LEDs 52 pulls the yellowish or greenish light from the BSY orBSG LEDs 52 to a desired color point on or near the BBL. Notably, thered LEDs 52 may have LED chips 54 that natively emit reddish lightwherein no wavelength conversion material is employed. Alternatively,the LED chips 54 may be associated with a wavelength conversionmaterial, wherein the resultant light emitted from the wavelengthconversion material and any light that is emitted from the LED chips 54without being absorbed by the wavelength conversion material mixes toform the desired reddish light.

The blue LED chip 54 used to form either the BSY or BSG LEDs 52 may beformed from a gallium nitride (GaN), indium gallium nitride (InGaN),zinc selenide (ZnSe), or like material system. The red LED chip 54 maybe formed from an aluminum indium gallium nitride (AlInGaP), galliumphosphide (GaP), aluminum gallium arsenide (AlGaAs), or like materialsystem. Exemplary yellow phosphors include cerium-doped yttrium aluminumgarnet (YAG:Ce), yellow BOSE (Ba, O, Sr, Si, Eu) phosphors, and thelike. Exemplary green phosphors include green BOSE phosphors, Lutetiumaluminum garnet (LuAg), cerium doped LuAg (LuAg:Ce), Maui M535 fromLightscape Materials, Inc. of 201 Washington Road, Princeton, N.J.08540, and the like. The above LED architectures, phosphors, andmaterial systems are merely exemplary and are not intended to provide anexhaustive listing of architectures, phosphors, and materials systemsthat are applicable to the concepts disclosed herein.

The control module electronics 28 for driving the array of LEDs 50 isillustrated in FIG. 9A according to a first embodiment of thedisclosure. As illustrated, the array of LEDs 50 may include a mixtureof red LEDs 52 and either BSY or BSG LEDs 52. The array of LEDs 50 iselectrically divided into two or more strings of series connected LEDs52. As depicted, there are three LED strings S1, S2, and S3. Forclarity, the reference number “52” will include a subscript indicativeof the color of the LED 52 in the following text where ‘R’ correspondsto red, BSY corresponds to blue shifted yellow, BSG corresponds to blueshifted green, and BSX corresponds to either BSG or BSY LEDs. LED stringS1 includes a number of red LEDs 52 _(R), LED string S2 includes anumber of either BSY or BSG LEDs 52 _(BSX), and LED string S3 includes anumber of either BSY or BSG LEDs 52 _(BSX). The control moduleelectronics 28 control the current delivered to the respective LEDstrings S1, S2, and S3. The current used to drive the LEDs 52 isgenerally pulse width modulated (PWM), wherein the duty cycle of thepulsed current controls the intensity of the light emitted from the LEDs52.

The BSY or BSG LEDs 52 _(BSX) in the second LED string S2 may beselected to have a slightly more bluish hue (less yellowish or greenishhue) than the BSY or BSG LEDs 52 _(BSX) in the third LED string S3. Assuch, the current flowing through the second and third strings S2 and S3may be tuned to control the yellowish or greenish light that iseffectively emitted by the BSY or BSG LEDs 52 _(BSX) of the second andthird LED strings S2, S3. By controlling the relative intensities of theyellowish or greenish light emitted from the differently hued BSY or BSGLEDs 52 _(BSX) of the second and third LED strings S2, S3, the hue ofthe combined yellowish or greenish light from the second and third LEDstrings S2, S3 may be controlled in a desired fashion.

The ratio of current provided through the red LEDs 52 _(R) of the firstLED string S1 relative to the currents provided through the BSY or BSGLEDs 52 _(BSX) of the second and third LED strings S2 and S3 may beadjusted to effectively control the relative intensities of the reddishlight emitted from the red LEDs 52 _(R) and the combined yellowish orgreenish light emitted from the various BSY or BSG LEDs 52 _(BSX). Assuch, the intensity and the color point of the yellowish or greenishlight from BSY or BSG LEDs 52 _(BSX) can be set relative the intensityof the reddish light emitted from the red LEDs 52 _(R). The resultantyellowish or greenish light mixes with the reddish light to generatewhite light that has a desired color temperature and falls within adesired proximity of the BBL.

The control module electronics 28 depicted in FIG. 9A generally includerectifier and power factor correction (PFC) circuitry 76, conversioncircuitry 78, and current control circuitry 80. The rectifier and powerfactor correction circuitry 76 is adapted to receive an AC power signal(AC IN), rectify the AC power signal, and correct the power factor ofthe AC power signal. The resultant signal is provided to the conversioncircuitry 78, which converts the rectified AC power signal to a DCsignal. The DC signal may be boosted or bucked to one or more desired DCvoltages by DC-DC converter circuitry, which is provided by theconversion circuitry 78. A DC voltage is provided to the first end ofeach of the LED strings S1, S2, and S3. The same or different DC voltageis also provided to the current control circuitry 80.

The current control circuitry 80 is coupled to the second end of each ofthe LED strings S1, S2, and S3. Based on any number of fixed or dynamicparameters, the current control circuitry 80 may individually controlthe pulse width modulated current that flows through the respective LEDstrings S1, S2, and S3 such that the resultant white light emitted fromthe LED strings S1, S2, and S3 has a desired color temperature and fallswithin a desired proximity of the BBL.

In certain instances, an external dimming device provides the AC powersignal. The rectifier and PFC circuitry 76 may be configured to detectthe relative amount of dimming associated with the AC power signal andprovide a corresponding dimming signal to the current control circuitry80. Based on the dimming signal, the current control circuitry 80 willadjust the current provided to each of the LED strings S1, S2, and S3 toeffectively reduce the intensity of the resultant white light emittedfrom the LED strings S1, S2, and S3 while maintaining the desired colortemperature.

The current control circuitry 80 may also adjust the current provided toone or more of the LED strings S1, S2, and S3 to control the colorrendering metric, such as the CRI or CQI, of the resultant white lightemitted from the LED strings S1, S2, and S3 at various overallbrightness levels, color temperatures, and the like. At a high level,the current control circuitry 80 is able to monitor ambient light thatis being provided by another source alone or in combination with thelight emitted from the lighting fixture 10 through an ambient lightsensor, such as the ambient light sensor 82 shown in FIG. 9A. Based on aselect characteristic or set of characteristics of the ambient lightthat are indicative of the color rendering metric, such as CRI or CQI,of the ambient light, the current control circuitry 80 may adjust thecurrent provided to one or more of the LED strings S1, S2, and S3.

For example, if the ambient light characteristic is indicative of theambient light having a lower color rendering metric (CRI/CQI), thecurrent control circuitry 80 will drive the LED strings S1, S2, and S3to emit light with a defined color rendering metric. If the ambientlight characteristic is indicative of the ambient light having a highercolor rendering metric, the current control circuitry 80 will drive theLED strings S1, S2, and S3 to emit light with a reduced color renderingmetric, which is lower than the defined color rendering metric.

For instance, when there is no ambient light or ambient light having alower color rendering metric, the current control circuitry 80 mayoperate normally and emit light having the defined color renderingmetric. In the presence of significant ambient light from sunlight,which naturally has a high color rendering metric, or other source thatis capable of providing ambient light with a relatively high colorrendering metric, the lighting component may adjust how the LED stringsS1, S2, and S3 are driven to emit light at a lower color renderingindex. The reduction in the color rendering metric of the emitted lightmay correspond to an increase in overall system efficiency, efficacy ofthe emitted light, a reduction in power consumption, or the like whilemaintaining perceived brightness.

In a system where the color rendering metric is CRI, the current controlcircuitry 80 may adjust the current in the LED strings S1, S2, and S3 toprovide a CRI of 90 or greater when there is no ambient light or whenthe ambient light is found to have characteristics indicative of theambient light having a lower or poor CRI. However, the current controlcircuitry 80 may adjust the current in the LED strings S1, S2, and S3 toprovide a CRI of 80 or less when there is a significant amount ofambient light having a relatively high CRI, such as when the ambientlight is provided by the sun or high-CRI rated incandescent lighting.

Reasons to reduce the color rendering metric of the light emitted fromthe lighting fixture 10 in the presence of ambient light that renderscolors well is to improve the overall efficiency of the lighting fixture10, improve the efficacy of the emitted light, reduce power consumption,or the like while maintaining the same intensity, perceived brightness,or the like. The gains in efficiency or reductions in power consumptionare due to the fact that it is generally more efficient to generate lowquality light than it is high quality light.

For example, BSY or BSG LEDs 52 _(BSX) in the LED strings S1 and S2 aregenerally much more efficient than the red LEDs 52 _(R) of LED stringS3. A significant amount of reddish light from the red LEDs 52 _(R) ofLED string S3 is required to be mixed with the yellowish or greenishlight from the BSY or BSG LEDs 52 _(BSX) in the LED strings S1 and S2 toprovide a resultant white light that renders colors well. If the amountof the red light from the red LEDs 52 _(R) of LED string S3 is reducedrelative the amount of the yellowish or greenish light, the colorrendering capabilities of the resultant light will be reduced. However,if there is a significant amount of high-CRI ambient light availablefrom another source, such as the sun, the reduction in the CRI from thelight emitted from the lighting fixture 10 will not be as noticeable, ifat all, when the ambient light and the light emitted from the lightingfixture 10 mix with each other in the lighting environment. In essence,the abundance of reddish light in the sunlight may substantiallycompensate for any reduction in reddish light provided by the lightingfixture 10.

In many instances, the BSY or BSG LEDs 52 _(BSX) in the LED strings S2and S3 are very efficient and can be driven the same or harder toincrease the output of the yellowish or greenish light and therelatively inefficient red LEDs 52 _(R) of LED string S1 may be drivenless hard while the overall intensity or perceived brightness of thelight output from the lighting fixture 10 remains substantially thesame, albeit with less color rendering capabilities. By reducing thereddish light from the red LEDs 52 _(R) of LED string S1, the overallefficiency of the lighting fixture 10 may be increased or the overallpower consumption of the lighting fixture 10 may be decreased duringperiods when the lighting fixture 10 does not need to output lighthaving relatively high color rendering capabilities.

In operation, the current control circuitry 80 may initially power onand the drive currents for the red LEDs 52 _(R) of LED string S1 and theBSY or BSG LEDs 52 _(BSX) in the LED strings S2 and S3 such that lightwith a normal (or higher) CRI, such as 90 or greater, is provided. Thecurrent control circuitry 80 will begin monitoring the ambient light viathe ambient light sensor 82 and analyze characteristics of the ambientlight that would allow the lighting fixture 10 to provide lower CRIlight. In the illustrated embodiment, when there is reddish light fromsunlight or another remote source, the current control circuitry 80 viathe ambient light sensor 82 can detect this condition and respond byreducing the drive current provided to the less efficient red LEDs 52_(R) of LED string S1. The drive currents provided to the BSY or BSGLEDs 52 _(BSX) in the LED strings S2 and S3 may be maintained, whereinthe overall intensity of the light from the lighting fixture 10 isdecreased as a result of reducing the amount of reddish light providedby the red LEDs 52 _(R) of LED string S1.

To avoid the perceived reduction in intensity of the light from thelighting fixture 10 when the drive current for the red LEDs 52 _(R) ofLED string S1 is reduced, the drive currents provided to the BSY or BSGLEDs 52 _(BSX) in the LED strings S2 and S3 may be increased asnecessary to maintain the desired level of intensity. In this instance,efficiency is gained or at least power consumption is decreased becauseof the different efficiency of red LEDs 52 _(R) of LED string S1 and theBSY or BSG LEDs 52 _(BSX) in the LED strings S2 and S3. When thelighting fixture is initially powered on, the current control circuitry80 may alternatively check the ambient light before providing any drivecurrent to the various LEDs 52. Once the ambient light is analyzed forthe presence of reddish light, the current control circuitry 80 maydetermine whether to provide drive currents to the LEDs 52 for normal(higher) CRI light in the absence of sufficient reddish content in theambient light or lower CRI light when there is sufficient reddishcontent in the ambient light.

The ambient light sensor 82 and the current control circuitry 80 may beconfigured to analyze a limited spectrum of ambient light or analyze abroad spectrum of the ambient light. For example, the relative amountsof the various primary colors, such as red, green, and blue (RGB), maybe analyzed based on the type of LEDs 52 being used to generate thelight. The LEDs 52 need not be BSY, BSG, or red LEDs. Any combination oftwo or more types of LEDs 52 may benefit from the concepts providedherein. For example, the LEDs 52 may include a first string of highlyefficient white LEDs and a second string of less efficient white LEDs,wherein the light from the highly efficient white LEDs does not rendercolors nearly as well as the light from the less efficient white LEDs.However, the light from the different white LEDs may be combined togenerate high CRI light, if the less efficient white (and better colorrendering) LEDs are driven relatively hard.

In the presence of high CRI ambient light, the current control circuitry80 may reduce the drive currents provided to the less efficient whiteLEDs and either maintain or increase the drive currents provided to themore efficient (and worse color rendering) LEDs. As a result, theoverall efficiency of the lighting fixture 10 is increased or theoverall power consumption is reduced by configuring the lighting fixture10 to provide light with a lower CRI. In general, the lighting fixture10 is able to respond to ambient lighting conditions that allow it toreduce the overall CRI of the emitted light without being overtlynoticeable to the human eye. Of course, the amount of reduction may becontinuously variable based on ambient lighting conditions and may beset based on the design objectives of the designer.

As illustrated in FIG. 9B, the ambient lighting sensor 82 (of FIG. 9A)may be another LED 82′ that is capable of generating current in responseto ambient light, and in particular, to ambient light having a desiredcolor rendering characteristic. For example, the LED 82′ may be same orsimilar to the red LEDs 52 _(R) of LED string S1. As such, in thepresence of reddish light that is similar to that emitted from the redLEDs 52 _(R) of LED string S1, the LED 82′ will generate currentproportional to the amount of reddish light available in the ambientlight. When the reddish light in the ambient light exceeds a definedthreshold, the drive currents provided to the red LEDs 52 _(R) of LEDstring S1 may be reduced a certain amount. Alternatively, the drivecurrents provided to the red LEDs 52 _(R) of LED string S1 may beinversely varied in proportion to the amount of reddish light availablein the ambient light. As such, the CRI of the overall light of thelighting fixture 10 may be reduced in a step-wise fashion in one or moresteps or may be continuously varied based on the amount of reddish lightavailable in the ambient light. Since the LEDs 52 may be driven withcurrent pulses of a PWM signal, the current control circuitry maymonitor the amount of reddish light or other characteristic of theambient light via the LED 82′ in between current pulses being providedto the LEDs 52.

In certain embodiments, certain of the LEDs 52 may be used to both emitlight as well as monitor a characteristic of the ambient light. One sucharrangement is shown in FIG. 9C. For example, one or more of the redLEDs 52 _(R), which are used to emit reddish light when presented thecurrent pulses via the string S1, may be used to monitor the amount ofreddish light in the ambient light between the current pulses. Based onthe amount of the reddish light in the ambient light, the currentcontrol circuitry 80 can control the amount of drive current provided tothe red LEDs 52 _(R) of LED string S1 as well as the BSY or BSG LEDs 52_(BSX) in the LED strings S2 and S3 to vary the CRI of the overall lightemitted from the lighting fixture 10 in a controlled fashion based onthe ambient light.

With reference to FIG. 9D, the intensity or color of the light emittedfrom the LEDs 52 may be affected by ambient temperature. If associatedwith a thermistor 84 or other temperature sensing device, the currentcontrol circuitry 80 can control the current provided to each of the LEDstrings S1, S2, and S3 based on ambient temperature in an effort tocompensate for adverse temperature effects. The intensity or color ofthe light emitted from the LEDs 52 may also change over time. Ifassociated with an optical sensor 86, the current control circuitry 80can measure the color of the resultant white light being generated bythe LED strings S1, S2, and S3 and adjust the current provided to eachof the LED strings S1, S2, and S3 to ensure that the resultant whitelight maintains a desired color temperature.

While CRI was used as an exemplary color rendering metric for the aboveexample, CQS or other desired metric is applicable to the conceptsprovided herein. Those skilled in the art will recognize improvementsand modifications to the embodiments of the present disclosure. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

What is claimed is:
 1. A lighting component comprising: a plurality ofLEDs arranged to produce LED light emissions; at least one sensorconfigured to detect a condition indicative of an ambient lightcharacteristic, wherein the at least one sensor is configured to produceat least one sensor signal; and control circuitry arranged to drive theplurality of LEDs, wherein the control circuitry, responsive to the atleast one sensor signal, is configured to adjust a color renderingmetric of the LED light emissions based on the ambient lightcharacteristic; wherein: the plurality of LEDs comprises at least onefirst emitter comprising a blue shifted yellow or a blue shifted greenLED, and at least one second emitter comprising a blue shifted yellow ora blue shifted green LED; the at least one second emitter providesemissions having a different color point than emissions provided by theat least one first emitter; and the control circuitry is configured todrive the at least one first emitter independently from the at least onesecond emitter.
 2. The lighting component of claim 1, wherein the atleast one sensor comprises an ambient light sensor.
 3. The lightingcomponent of claim 1, wherein the at least one sensor comprises anoptical sensor arranged to detect a condition indicative of illuminationgenerated by the lighting component.
 4. The lighting component of claim1, wherein the at least one sensor comprises a temperature sensor. 5.The lighting component of claim 1, wherein the plurality of LEDs furthercomprises at least one third emitter comprising a reddish LED, and thecontrol circuitry is configured to drive the at least one third emitterindependently from the at least one first emitter and the at least onesecond emitter.
 6. A lighting component, comprising: a plurality of LEDsarranged to produce LED light emissions; at least one sensor configuredto detect a condition indicative of an ambient light characteristic,wherein the at least one sensor is configured to produce at least onesensor signal; and control circuitry arranged to drive the plurality ofLEDs, wherein the control circuitry, responsive to the at least onesensor signal, is configured to adjust a color rendering metric of theLED light emissions based on the ambient light characteristic; wherein:the control circuitry is configured to drive the plurality of LEDs toprovide LED light emissions having a normal color rendering metric, ifthe at least one sensor signal indicates that the ambient lightcharacteristic has a lower color rendering metric; the control circuitryis configured to drive the plurality of LEDs to provide LED lightemissions having a reduced color rendering metric, if the at least onesensor signal indicates that the ambient light characteristic has ahigher color rendering metric; and the reduced color rendering metric islower than the normal color rendering metric.
 7. The lighting componentof claim 6, wherein the LED light emissions having the normal colorrendering metric and the LED light emissions having the reduced colorrendering metric have substantially a same intensity.
 8. The lightingcomponent of claim 6, wherein the lighting component consumes less powerwhen providing the LED light emissions having the reduced colorrendering metric than when providing the LED light emissions having thenormal color rendering metric.
 9. A method for operating a lightingcomponent including a plurality of LEDs, the method comprising:utilizing at least one sensor to detect a condition indicative of anambient light characteristic, wherein the at least one sensor producesat least one sensor signal; driving the plurality of LEDs with controlcircuitry, responsive to the at least one sensor signal, to adjust acolor rendering metric of LED light emissions based on the ambient lightcharacteristic; driving, with the control circuitry, at least one firstemitter of the plurality of LEDs independently from at least one secondemitter of the plurality of LEDs, the at least one first emittercomprising a blue shifted yellow or a blue shifted green LED, and the atleast one second emitter comprising a blue shifted yellow or a blueshifted green LED; providing, by the at least one first emitter,emissions having a color point; and providing, by the at least onesecond emitter, emissions having a different color point than theemissions provided by the at least one first emitter.
 10. The method ofclaim 9, wherein the at least one sensor is utilized to detect acondition indicative of illumination generated by the lightingcomponent.
 11. The method of claim 10, wherein the at least one sensorcomprises an optical sensor.
 12. The method of claim 9, wherein the atleast one sensor comprises an ambient light sensor.
 13. The method ofclaim 9, wherein the at least one sensor comprises a temperature sensor.14. The method of claim 9, further comprising driving at least one thirdemitter of the plurality of LEDs independently from the at least onefirst emitter and the at least one second emitter, wherein the at leastone third emitter comprises a reddish LED.
 15. A method for operating alighting component including a plurality of LEDs, the method comprising:utilizing at least one sensor to detect a condition indicative of anambient light characteristic, wherein the at least one sensor producesat least one sensor signal; driving the plurality of LEDs with controlcircuitry, responsive to the at least one sensor signal, to adjust acolor rendering metric of LED light emissions based on the ambient lightcharacteristic; driving the plurality of LEDs to provide LED lightemissions having a normal color rendering metric, if the at least onesensor signal indicates that the ambient light characteristic has alower color rendering metric; and driving the plurality of LEDs toprovide LED light emissions having a reduced color rendering metric, ifthe at least one sensor signal indicates that the ambient lightcharacteristic has a higher color rendering metric; wherein the reducedcolor rendering metric is lower than the normal color rendering metric.16. The method of claim 15, wherein the LED light emissions having thenormal color rendering metric and the LED light emissions having thereduced color rendering metric have substantially a same intensity. 17.The method of claim 15, wherein the lighting component consumes lesspower when providing the LED light emissions having the reduced colorrendering metric than when providing the LED light emissions having thenormal color rendering metric.
 18. A lighting component comprising: aplurality of LEDs arranged to produce LED light emissions; and controlcircuitry arranged to drive the plurality of LEDs; wherein: the controlcircuitry is arranged to receive at least one signal, and the controlcircuitry is configured to adjust a color rendering metric of the LEDlight emissions responsive to the at least one signal; the controlcircuitry is configured to drive the plurality of LEDs to provide LEDlight emissions having a normal color rendering metric, if the at leastone signal is indicative of a condition in which ambient illuminationhas a lower color rendering metric; the control circuitry is configuredto drive the plurality of LEDs to provide LED light emissions having areduced color rendering metric, if the at least one signal is indicativeof a condition in which ambient illumination has a higher colorrendering metric; and the reduced color rendering metric is lower thanthe normal color rendering metric.
 19. The lighting component of claim18, wherein the control circuitry is configured to adjust a colorrendering metric of the LED light emissions responsive to the at leastone signal while maintaining substantially unchanged at least one of thefollowing items (i) or (ii): (i) intensity of the LED light emissions,or (ii) color temperature of the LED light emissions.
 20. The lightingcomponent of claim 18, further comprising at least one sensor configuredto detect a condition indicative of at least one of (i) illuminationgenerated by the lighting component or (ii) illumination in a lightingenvironment proximate to the lighting component.